This application is related to and claims benefit of priority to Swedish Patent Application No. 9903521-4, filed Sep. 27, 1999, entitled xe2x80x9cCONNECTION OF AN ADD/DROP NODE,xe2x80x9d which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an optical communication system, in particular to an add/drop node of an optical WDM (Wavelength Division Multiplexing) network.
2. Discussion of the Background
Optical networks using WDM (Wavelength Division Multiplexing) technology are become more and more prevalent. These networks utilize a number of add/drop nodes that are interconnected; as the number of nodes increases, the complexity of the connections also increases. A simple approach is needed to connect these add/drop nodes to the network. In addition, upgrades to the add/drop nodes should likewise be simple. For example, when the capabilities of an existing add/drop node is expanded to operate at another wavelength band, the work that is required to upgrade the add/drop node should be minimized.
It is an object of the invention to provide an add/drop node for an optical WDM-network that has a simple mechanism to connect the node to the circulating fiber paths of the network.
According to one aspect of the invention, an add/drop node used in an optical network having two fiber paths for carrying light corresponding to a plurality of channels in opposite directions comprises a pair of add/drop modules that correspond to one of the plurality of channels. Each of the add/drop modules includes an add device that is configured to add light to one of the fiber paths, and a drop device configured to deflect a portion of the light from another one of the fibers paths. The pair of add/drop modules have identical construction. The above arrangement advantageously provides a simple approach for connecting the components of an add/drop node.
According to another aspect of the invention, an optical communication system comprises a plurality of fiber paths that carry optical signals corresponding to a plurality of channels in opposite directions. A plurality of add/drop nodes are coupled to the fiber paths. Each of the add/drop nodes includes a pair of add/drop modules that corresponds to one of the plurality of channels. Further, each of the add/drop modules includes an add device that is configured to add light to one of the fiber paths, and a drop device that is configured to deflect a portion of the light from another one of the fibers paths. The pair of add/drop modules have identical construction. The above approach simplifies scaling of the add/drop node.
According to yet another aspect of the invention, an add/drop node used in an optical network having two fiber paths for carrying light corresponding to a plurality of channels in opposite directions comprises a pair of add/drop modules that correspond to one of the plurality of channels. Each of the add/drop modules includes a means for adding light to one of the fiber paths, and a means for deflecting a portion of the light from another one of the fibers paths. The pair of add/drop modules have identical construction. The above arrangement advantageously permits ease of expanding the capabilities of the add/drop node.